ML20203B116

Forwards SER Section 6.4 Open Items Associated w/AP600 Main Control Room Habitability Sys

ML20203B116
Person / Time
Site:	05200003
Issue date:	12/08/1997
From:	Huffman W NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9712120340
Download: ML20203B116 (8)

Text

December 8, 1997 Mr. Nicholas J. Liparuto, Manager Nuclear Safety and Regubtory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230

SUBJECT:

OPEN ITEMS ASSOCIATED WITH THE AP600 SAFETY EVALUATION REPORT (SER) ON THE AP600 MAIN CONTROL ROOM HABITABILITY SYSTEM

Dear Mr. Liparulo:

The Plant Systems Branch of the U.S. Nuclear Regulatory Commission (NRC) has provided the SER input to the Standardization Project Directorate on the AP600 main control room habitability system, SER Section 6.4. The input has open items which have been extracted and designated as final safety evaluation report (FSER) open items in the enclosure to this letter. Open items from the Radiation Protection Branch concerning the radiological consequence assessment of the main control room habitability system have already been forwarded to Westinghouse under FSER Open items 470.41F through 470.44F,440.46F, and NRC letter to Westinghouse dated July 23,1997.

If you have any questions re0arding this matter, you may contact me at (301) 4151141.

Sincerely, original signed by:

William C. Huffman, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No. 52 003

Enclosure:

As stated cc w/ encl: See next page DISTRIBUTION:

Docket File PDST R/F TQuay 1

PUBLIC TKenyon WHuffman 1

JSebrosky DScaletti JNWilson ACRS (11)

WDean,0-5 E23 JMoore,0-15 B18 JRaval,0-8 D1 CCarpenter,0-8 D1 LMarsh,0-8 D1 SNewbeny,0 8 E2 GHolahan,0-8 E2 DOCUMENT NAME: A:SER6-4.Ol To recolve a copy of this document, Indicate in the box: "C" = Copy without attachment / enclosure

E" = Copy with rttachment/ enclosure "N" = No copy OFFICE PM:PDST:DRPM D:PDST:DRPM3 l

l NAME WCHuffmankgDWTROuay [/T ro DATE 12/ 5 /97

12/4 /97 Vi / F OFFItAL RECORD COPY Iglll}'lll'llll 9712120340 971200 PDR ADOCK 05200003

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Mr. Nicholas J. Liparuto Docket No. 52 003 Westinghouse Electric Corporation AP600 cc:

Mr. B. A. McIntyre Mr. Russ Bell Advanced Plant Safety & Licensing Senior Project Manager, Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 i Street, NW P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006 3706 Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Dr. Craig D. Sawyer, Manager Advanced Reactor Pro 0 rams Mr. Sterling Franks GE Nuclear Energy U.S. Department of Energy 175 Curtner Avenue, MC-754 NE 50 San Jose, CA 95125 19901 Germantown Road Germantown, MD 20874 kr. Robert H. Buchholz GE Nuclear Energy Mr. Frank A. Ross 175 Curtner Avenue, MC 781 U.S. Department of Energy, NE-42 San Jose, CA 95125 Office of LWR Safety and Technology 19901 Germantown Road Barton Z. Cowan, Esq.

Germantown, MD 20874 Eckert Seamans Cherin & Mellott 600 Grant Street 42nd Floor Mr. Charies Thompson, Nuclear Engineer Pittsburgh, PA 15219 AP600 Certification NE 50 Mr. Ed Rodwell, Manager 19901 Germantown Road PWR Design Certification Germantown, MD 20874 Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303 l

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SER SECTION 6.4 OPEN ITEMS ASSOCIATED WITH THE AP600 CONTROL ROOM HABIT-ABILITY SYSTEM 410.366F in accordance with TMI Action Plan item lli.D.3.4, COL applicants referencing the AP600 design must demonstrate that control room operators are adequately protected against the effects of the release of toxic substances either on or off site, and that the plant can be safely operated or shut down under conditions created by any design-basis accident. The COL applicant must also determine the amounts and locations of any possible sources of toxic substances near the plant using the methods in RG 1.78 and RG 1.95. The COL applicant must provide toxic gas detectors where necessary to petmit automatic isolation of the control room. This was a DSER COL Action item 6.4-1. In the text of SSAR Section 6.4.7 Westinghouse states that COL applicants referencing the AP600 design are responsible for the amount and location of possible sources of toxic chemicals in or near the plant and toxic gas monitoring as required, and that RGs 1.78 and 1.95 address control room protection for toxic chemicals.

(a)

Westinghouse needs to state specifically that COL applicants referencing the AP600 certified design are responsible for the amount and location of possible sources of toxic chemicals in or near the plant and for seismic Category 1 Class 1E toxic gas monitoring as required, and is also responsible for evaluating and off site toxic releases in accordance with the guidelines of RGs 1.78 and 1.95 in order to meet the requirements of TMI Action Plan item lil.D.3.4 and GDC 19.

(b) in the unlikely event that power to the VBS is unavailable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, MCR habitability is mair:tained by operating one of two MRC ancillary fans to supply outside air to the MRC. Westinghouse believes that the outside air will be acceptable for use within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following a radiological release. However, Westinghouse needs to provide additionalinformation in the SSAR on the Post 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> toxic gas actions. Since Westing.

Muse has stated that this is the responsibility of the COL applicant, Westinghouse needs to state specifically that COL applicants referencing the AP600 certified design are responsible for evaluating the Post 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> on and off site toxic releases in accordance with the guidelines of RGs 1.78 and 1.95 in order to meet the requirements of TMl Action Plan item lil.D.3.4 and GDC 19, 410.367F Westinghouse needs to state in SSAR Section 6.4.7 specifically that the COL applicants referencing the AP600 certified design are responsible for verifying that the as-built design, procedures, and trring are consistent with the licensing basis documentation and the intent of Generic Issue 83.

410.368F The use of noncombustible construction and heat and flame resistant materials throughout the plant to reduce the likelihood of fire and consequentialimpact on the MCR envelop atmosphere are evaluated in SER Section 9.5.1. Westinghouse previously listed the fire protection syttem i

(FPS) as one of the systems that collectively provide the habitability functions for the plant. This Enclosure

2 list was in SSAR Revisions up to and including Revision 4, it was subsequentty deleted in later SSAR revisions. Westinghouse needs to list and describe the FPS function as part of the habitability systems.

410.369F The MCR envelop (MCRE)is shown in Figures 6.41,1.2 6,12.31 and areas adjacent to the MCRE are shown in Figures 1.2 25 through 1.2 31 of the SSAR. SSAR Table 3.2 3 indicates that the VES is located in the auxiliary building, which is a missile-protected selsmic Category I building. However, in SSAR Section 6.4.2.1, Westinghouse needs to describe, the enveloping areas of the MCRE and the MCRE location including Elevation.

410.370F SSAR Figure 6.4 2 shows a single pressure instrument (PT001) located outside the MCR envelop. This pressure instrumentation was redundant in previous revisions of the SSAR. The VES is a safety related system that must meet the requirements of GDC 19, therefore the post-accident pressure instrumentation must be redundant to meet the single fallure criteria, it must be Class 1E and conform with RG 1.971983, Revision 3, and it must be seism!c Category 1.

Therefore, Westinghouse needs to revise the text of the SSAR, Figure 6.4-2 and Table 7.51 to reflect these changes.

410.371F Westinghouse needs to provide the following to clarify the VES flow design, temperature, and relative humidity criteria:

(a)

Revise SSAR Section 6.4.3.2 to provide specific minimum and maximum temperatures with the corresponding relative humidities for the MCRE during the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period following the onset of a postulated design basis accident. Also, provide (for NRC staff review) tir results of the evaluation performed (based on Gothic methodology or similar methodolo-gles employed) and associated assumptions made to anive at these temperatures and humidities.

(b)

State in the text of the SSAR that the VES flow capacity conforms to: (1) the MCRE flow design " Table 1, and Appendix C Table C 1," of ASHRAE Standard 621989, " Ventilation for Acceptablo Indoor Air Quality," and (2) 1993 ASHRAE Handbook, " Fundamentals St Edition," Chapter 23.2, " Ventilation and Indoor Air Quality," since these references provide the appropriate guidelines for maintaining the carbon dioxide concentration limits below one half percent by volume for a maximum occupancy of eleven persons inside the MCRE.

(c)

Justify why the above flow capacity is adequate enough to meet the prescribed limits of the contaminants described in Table 1, and Appendix C Table C-1, of ASHRAE Standard 621989, " Ventilation for Acceptable Indoor Air Quality."

(d)

Provide a revision designation letter to MIL-HDBK 759, 31 July 1995, " Human Engineering Guidelines," which is listed as a reference in SSAR Section 6.4.8.

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410.372F Westinghouse needs to provide following:

1.

Provide data in SSAR Section 6.4 2.3 for the VES pressure regulating valves, flow metering or4 ices, remo.ely operated isolation valves, manual isolation valves, pressure relief isolation valves, pressure relief dampers, and breathing apparatus. The data should include the specific ASME code class, AP600 classification and seismic category. In addition provide a functional description of the manualisolation valves and list these as references in SSAR Section 6.4.8.

2.

Provide a descriptioit and data in SSAR Section 6.4.2.3 for the VES piping and penetra-tions such as specific ASME code class, AP600 classification and seismic category and list these references in SSAR Section 6.4.8. Additionally, provide consistency in the text of the SSAR for the use of temtinology such as

• air Bottles

• and

• sir storage tanks,'l.e.,

are they air bottles or are they air storage tank 7 3.

Provide an evaluation of the air piping material that is alloy steel except piping from tanks to sub-headers is stainless steel, as shown in Figure 6.4 2, as to its suitability without any degradation such as corrosion or any other degradation which may degrade the quality of breathing air during the life of the plant and revise the text of the SSAR accordingly. Also, provide clarification concoming the

• loop" shown at the discharge side of each emergency air storage tank and revise SSAR Figure 6.4 2 accordingly.

4.

Verify that the above components are included in Table 3.2 3 of the SSAR with the proper code classification data, S.

SSAR Section 6.4.2.2 state that the VES air storage vessels have a combined minimum volume of 41.77 m'/se:(1475 cubic feet) while it is stated in SSAR Section 6.4.2.3 that the storage tanks collectively contain a minimum storage capacity of 8805.3 m'/sec (314,132 standard cubic feet). Clarify this storage capacity data with the appropriate pressure values and revise the text of the SSAR Sections accordingly. Also, provide a breakdown of air flow and corresponding design and operating pressures at various points of the VES including the.;utlet of the air storage tanks, outlet of pressure regulating valves, inlet to flow metering orifice in each train, and outlet to air flow metering orifice in each train, in order to show that the system can provide a total of 0.0306 m'/sec (65 scfm) of airflow, at a given time during accident conditions, ap -tated in SSAR Section 6.4.4. Revise itie text of the SSAR and Figure 6.41 to include ti ( nformation.

6.

SSAR Section 6.4.4 states that 60 scftr of ventilation flow is sufficient to pressurize the control room to at least 1/8 in water gauge differential pressure. This statement should be revised to state that 60 scfm of ventilation flow is sufficient to pressurize the control room to at least positive 1/8-in water gauge differential pressure with respect to the surroundings spaces.

410.373F Westinghouse needs to state specifically in the SSAR that no silicone sealant or any other patching material shall be used on VBS filters, housing, mounting frame, ducts, or penetrations and VES piping, valves, dampers, or penetrations forming the MCR pressure boundary.

4 410.374F Westinghouse needs to revise SSAR Section 6.4.2.4 to specifically state that there will be no adverse environmental effects to the MCR sealant materials from the spent fuel pool boiling events, as evaluated.

410.375F Westinghouse should revise the SSAR to include the following:

(a)

Revise SSA*t Section 9.4.1 (VBS) to state the VES carbon dioxide concentration limit and air flow criteria for normal and maximum occupancy of the areas served by VBS.

(b)

Revise SSAR Table 14.3 7 (Sheet 1 of 4)," Radiological Analysis", to reflect the VES flow rate 65 sc!m +/ 5 sefm.

410.376F in response to RAI Question 400.10.g, Westinghouse states that AP600 does not have an onsite chlorine or other toxic chemicals storage facility, and offsite chlorine or toxic release is site specific. However, SSAR Table 6.41, 'Onsite Chemicals," shows various chemicals. Addition-ally, in a letter dated October 10,1997, Westinghouse states, in response to a staffs concern for onsite chemicals, that chemicals listed in SSAR Table 6.41 were evaluated using the methodol-ogy in NUREG-0570, " Toxic Vapor Concentrations in the Control Room Following A Postulated Accidental Release," and concluded that these chemicals do not represent a toxic hazard to control room operators. Also, SSAR Section 6.4.4 states that analysis of onsite chemicals as described in SSAR Table 6.41 and their locations as shown in SSAR Figute 1.2 2 are in accordance with RG 1.78 and shows that these sources do not represent a toxic hazard to MCRE personnel. Therefore, Westinghouse needs to update the response to RAI Ques-tion 450.10.g and provide the results of these evaluations (conformance with NUREG 0570 and RG 1.78) and associated assumptions to meet the requirements of GDC 19 with the following details:

1.

Amount and name of chemicals stored in individual storage cylinders and number of cylinders 2.

Overall dimensions and locations of cylinders 3.

Pressure of each cylinder 410.377F The non safety related VBS subsystem (MCR/ technical support center HVAC subsystem) isolatos the MCRE and/or TSC area from the normal outdoor air intake, it provides filtered outdoor air to pressurize the MCRE and TSC areas to a positive pressure of at least 3.2 mm (1I8-in) water gauge, with respect to the surrounding areas, when "high" gaseous radioactivity is detected in the MCRE supply duct. As described in SSAR Section 6.4.3.2, in the event of a "high high' signal for particulate or iodine radioactivity in the MCRE supply duct or loss of ac power sources, the redundant safety-related VBS supply and retum isolation valves, located in the MCRE, close and at the same time safety-related VES bsgins to deliver air from the emergency air storage tanks to the MCRE by automatically opening the isolation valves located

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In the supply line to protect the MCR occupants from a potential radiation release. After a slight time delay, in which the MCRE pressure increases slightly due to the addition of air, the isolation valves cpon, allowing the pressure relief dampers to function. However, Westinghouse needs to state in specific terms exactly what amount of time delay and MCRE pressure incrosse is required to open these isolation valves, j

410.378F Air samples from the emergency air storage tanks are taken quederiy and analyzed to conform with the guidelines of Table C 2 of ASHRAE Standard 62. The staff has determined that reference to C 2 is not acceptable. However, conformance with both, Appendix C, Table C 1 l

and Table 1 of ASHRAE Standard 62, is acceptable. Additionally, Westinghouse must include the above ortleria as part of the Surveillance Requirements of Chapter 16 Technical Specifica-tions to validate the VES air quality of the emergency air storage tanks and air quality of the air supplied from the compressed and instrument air system (CAS) and revise SSAR Sec-tions 6.4.5.1,6.4.5.3 and g.4.1, and the VES Surveillance Requirements of Chapter 16 Technical Specifications.

410.37gF SSAR Table 15.6.5 2 provides the MCRE volume and maximum unfiltered air in-leakage (infiltration) rates as follows. The main control room envelope (MCRE) volume is 1010.g1 m' (35,700 ft'). The maximum unfiltered air in-leakage (infiltration)into the MCRE under accident conditions is 0.00117 0.00233 m*/sec (2.5 5.0 cfm) when the VES is operating. The maximum unfiltered air in leakage (infiltration) into the MCRE during a "high" gaseous radioactivity signal while the VBS is operating is 0.066 m*/sec (140 cfm). The AP600 design features such as a vestibule style entrance preventing contaminated air from entering the MCR envelope as a result of egress and int ass, and maintaining the MCRE at positive pressure, with respect to surround.

ing areas, are nc' uncommon. This design is quite prevalent at operating reactors and tnose reactors show comparatively much larger amounts (i.e., hundreds of cfm) of unfiltered in-leakages as has been determined by a tracer gas testing method. Non safety-related ductwork and associated equipment routed through the MCRE, such as the AP600 VBS design,

. can provide pathways for unfiltered in leakage of contaminated air from outside the MCR envelope, and can also helps to provide a falso indication of pressurization of the MCRE.

Pressurization testing measurements do not assure that the MCRE is at a uniform positive pressure with respect to adjacent areas because pockets in the MCRE may be at a negative or lower positive pressure with respect to adjacent areas and thus provide pathways for relatively larger amounts of additional unfiltered in leakage than assumed in dose calculations for postulated design basis accident conditions. Therefore, Westinghouse should validate the VES design. One of the acceptable methods of validation is testing in accordance with ASTM E741,

" Standard Test Method for Determining Air Leakage Rate by Tracer Dilution." Westinghouse -

needs to validate the VES design for the MCRE by tracer testing or its equivalent and revise.

i SSAR Sections 6,4 and g.4.1, and the VES Surveillance Requirements of Chapter 16 Technical Specifications.

/10.380F Pre-operational testing is discussed in Chapter 14 of this report. The staff has determined that 3

the air quality referer.co to Appendix C, Table C 2 of ASHRAE Standard 62, is not acceptable.

However, conformance with both, Appendix C, Table C-1 and Table 1 of ASHRAE Standard 62,

t 6-is acceptable, Therefore, Westinghouse needs to revise pre-operationalinspection and testing requirements of Chapter 14 for the VES and VBS to include the above criteria to validate the VES air quality Of the emergency air storage tanks and air quality of the air supplied from the CAS.

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